Dungeons and Dragons

Dungeons & Dragons (D&D) is a fantasy role-playing game (RPG) originally designed by Gary Gygax and Dave Arneson, and first published in 1974. The game has been published by Wizards of the Coast since 1997. It was derived from miniature war games with a variation of the Chainmail game serving as the initial rule system. D&D's publication is widely regarded as the beginning of modern role-playing games and the role-playing game industry.

D&D departs from traditional war gaming and assigns each player a specific character to play instead of a military formation. These characters embark upon imaginary adventures within a fantasy setting. A Dungeon Master serves as the game's referee and storyteller, while also maintaining the setting in which the adventures occur and playing the role of the inhabitants. The characters form a party that interacts with the setting's inhabitants (and each other). Together they solve dilemmas, engage in battles, and gather treasure and knowledge. In the process the characters earn experience points to become increasingly powerful over a series of sessions.

Episodes

"The Wiggly Finger Catalyst" (S5E4), the guys actually play D&D for the first time in the series; Sheldon conducts an experiment by making all of his minor decisions using his D&D dice to allow him to use all of his brain in his theoretical physics work.